1. Field of the Invention
This invention relates to respirator cartridges and has particular reference to improvements in end-of-service life indicators for organic vapor/gas filters.
2. Description of the Prior Art
Respirators using replaceable filter cartridges are commonly used for protection against a wide range or respiratory hazards which include toxic and/or disease producing dusts, mists, sprays, fumes, vapors or gases. The cartridges are replaced when their capacity to provide respiratory protection at or below hazardous concentration levels becomes apparent to the user or is otherwise arbitrarily or administratively determined.
As discussed in U.S. Pat. No. 4,154,586, windowed color changing indicators provide desirable means for monitoring the effectiveness of organic vapor respirator cartridges.
Heretofore, however, the shelf life of color indicators, e.g. of the type disclosed in U.S. Pat. No. 4,154,586, has been considerably shorter than that of the main cartridge sorbent. This, in addition to promoting premature disposal of the cartridges, i.e. while still having a useful absorbency to toxic vapors or gases, further requires costly inventory monitoring based upon useful life expectancies of the indicator chemicals per se.
Accordingly, a principal object of the present invention is to improve the shelf life of indicator systems and respirator cartridges with the corollary of extended cartridge usefulness and avoidance of cartridge use with spent or partially spent end-of-service life indicators.
Another object is to accomplish the above with end-of-service life indicating system improvement, e.g. improvement in the indicator system's ability to respond to both water soluble and water insoluble organic vapors.
Still another object is to accomplish faster than heretofore and more complete indicator system color change for a wide variety of organic vapors; and
Yet another object is to afford color indicator moisture protection during periods of cartridge non-use.
Other objects and advantages of the invention will become more readily apparent from the following description.